Conventionally, the electric power steering system has been known which includes: a steering shaft including an input shaft and an output shaft which are coaxially interconnected via a torsion bar; a cylindrical housing for rotatably supporting the steering shaft; a detector coil accommodated in the housing as surrounding the steering shaft in order to detect a torsion angle of the torsion bar; an electric motor for applying a steering assist force to the output shaft or a steering mechanism operatively coupled with the output shaft; a control board for controlling the steering assist force from the electric motor based on the variations of impedance produced in the detector coil; and a plurality of lead pins projecting from an outside periphery of the detector coil.
Such lead pins are inserted through through-holes formed in a substrate constituting the control board and are conductively connected thereto via solder (Japanese Unexamined Patent Publication No. 2003-11833 (FIG. 2)).